| Motion sickness(MS),is a special body reaction syndrome caused by the stimulation of unsuitable environment or unaccustomed factors in the environment.The main clinical manifestations of motion sickness are vestibular dysfunction syndrome,manifested by dizziness,pale face,cold sweat,nausea,vomiting,changes in blood pressure and pulse,and sometimes accompanied by headache.The symptoms can disappear quickly when patients get rid of the motion stimulation,but some patients can still have motion sickness symptoms last for 1-2 days.Motion sickness is a common and frequently occurring disease among flight cadets and flight personnel,and is also the main cause of flight suspension and school suspension.Precision medicine examination and vestibular function training are the main methods to prevent motion sickness in flight cadets and flight personnel.Through the selection of precision medicine,the pilot cadet candidates with high sensitivity are eliminated to avoid the occurrence of motion sickness during subsequent flight missions.Vestibular function training can improve the adaptability of the vestibular system and reduce the symptoms of vestibular discomfort,which plays an important role in reducing the occurrence of motion sickness.However,the underlying mechanism of reducing motion sickness through vestibular training has not been clearly defined.As a presynaptic membrane-associated protein involved in the release of neurotransmitters,synaptophysin has obvious immune activity in the afferent and efferent endings of the vestibular terminator and the afferent nerve endings around the vestibular type I hair cells,but its role in the pathogenesis of motion sickness and vestibular adaptation has not been reported.In order to provide important scientific basis and new prevention and treatment strategies for motion sickness,and provide guarantee for the improvement of combat effectiveness of military pilots,this study focuses on the specific role of synaptophysin,the synaptic remodeling regulatory factor,in the occurrence and development of motion sickness and its possible regulatory mechanism,Purpose: Animal models of motion sickness and vestibular adaptation in rats were established by trapezoidal rotation stimulation,and motion sickness indexes and symptoms of conditioned taste anorexia were used to evaluate the animal models.The changes of synaptophysin content in the utricle of motion sickness and vestibular adaptation rats were tested,and the changes of synaptophysin in the vestibular system of motion sickness and vestibular adaptation rats were identified.The effect of anisodamine on the expression of synaptophysin in rats was observed.Methods: In the first part,animal models of motion sickness and vestibular adaptation were established.72 SD male rats with stable 0.15 % saccharin water consumption were divided into two control groups,180°/s rotational stimulation group and 240°/s rotational stimulation group.Each group of rotational stimulation group was further divided into 15 min group,20 min group,25 min group,30 min group and 35 min group.There were 6 rats in each group.The consumption of 0.15 % saccharin water before and after 24 hours’ rotation stimulation and the motion sickness index after rotation stimulation were measured.Eighteen vestibular sensitive rats were randomly divided into three groups to receive rotational stimulation training,with 6 rats in each group.They were divided into daily rotational stimulation group,1-day interval of rotational stimulation group and 2-day interval rotational stimulation group,with each stimulation for 25 minutes.Saccharin water consumption and motion sickness index after rotational stimulation 24 hours were measured on days 1,3,7,14 and 21 after rotational exercise training.In the second part,the changes of synaptophysin content in the utricle of motion sickness and vestibular adaptation rats were observed.Sixteen male SD rats were randomly divided into two groups: control group and motion sickness group.The motion sickness group rats were stimulated by rotational motion at 240°/s for 25 min.Forty-eight male SD rats were divided into 6 groups: vestibular insensitivity without rotation group,vestibular sensitivity without rotation group,vestibular sensitivity with single rotation,vestibular sensitivity with continuous rotation for 7 d,vestibular sensitivity with continuous rotation for 14 d,vestibular sensitivity with continuous rotation for 21 d.The continuous rotation group rats were subjected to rotational motion stimulation of 240°/s for 30 min every day.The content of synaptophysin in the vestibule of rats was observed by WB and immunofluorescence.In the third part,to observe the effect of anisodamine on the expression of synaptophysin in vestibular system of rats with motion sickness.Sixteen male SD rats aged 6 weeks were randomly divided into 2 groups,the motion sickness group and the anisodamine group,with 8 groups in each group.The animals in both groups were stimulated with 240°/s rotational motion for 25 min.Anisodamine group rats were given anisodamine intragastric administration before rotation stimulation.The severity of motion sickness was assessed by conditioned taste anorexia and motion sickness index,and the content of synaptophysin in the utricle was detected by WB.Results: In the first part,the consumption of 0.15 % saccharin water in 180°/s rotational exercise stimulation group did not change significantly under different rotational exercise stimulation time,and motion sickness index increased with the extension of rotational exercise stimulation time.After 25 min,30 min and 35 min of the240°/s rotary exercise stimulation group,the saccharin water consumption decreased significantly,and motion sickness index was the highest in the 25 min rotary exercise stimulation group.On the 7th and 14 th day,saccharin water consumption of vestibular sensitive rats underwent daily continuous rotation training decreased significantly,and recovered to the level before training on the 21 st day,while motion sickness index showed a gradually decreasing trend.There was no significant change in saccharin water consumption of vestibular sensitive rats after 1 day and 2 day rotation training,and motion sickness index remained at a high level in the last day of training.In the second part,there was no significant change in the content of synaptophysin in the vestibular insensitive group before and after rotational exercise stimulation,but the content of synaptophysin in the vestibular sensitive group increased significantly after a single rotational stimulation.After continuous rotation for 7 days and 14 days,the content of synaptophysin in the vestibular sensitive group decreased comparing with the vestibular sensitive single rotation group,but there was no significant difference.After21 days of continuous rotation,the content of synaptophysin in the utricle decreased significantly compared with that in vestibular sensitive single rotation group.In the third part,the 0.15 % saccharin water consumption of rats in the motion sickness group was significantly reduced after the rotational motion stimulation,while the 0.15 % saccharin water consumption of rats in the anisodamine group was not significantly changed before and after the rotational motion stimulation.The motion sickness index of anisodamine group was significantly lower than motion sickness group after rotational motion stimulation,and the content of synaptophysin in the utricle of anisodamine group was significantly lower than motion sickness group.Conclusion: The rat model of motion sickness and vestibular adaptation has been established successfully.Synaptophysin in the utricle of vestibular system may play a role in the pathogenesis of motion sickness and vestibular adaptation. |
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